The c-ets oncogene was originally discovered through its viral equivalent v-ets gene of the avian acute leukemia virus, E26. This oncogene codes for nuclear proteins against which a number of monoclonal antibodies have been raised. These antibodies were used to check for ets protein expression in bacterial (E. coli w3110) and yeast (S288C haploid) cells. The antibody directed against the 56 Kd ets-2 protein was found to give a signal in yeast cells, as well as in the COLO 320 double-minute (DM) cells used as a positive control, but failed to do so in the bacterial cells. In addition, a new monoclonal antibody tested was found to give a positive signal in both the yeast and the human COLO 320 DM cells.